Method and composition for reducing octane requirement increase



U it d t tes Patent o,

3: 144 311 WTHOD AND CGMiGSiTION FOR REDUQHNG OCTANE REQUHQEMENT INCREASE Jack W. Armstrong, East Brunswick, N.J., and Richard L. Woorlrutf, Walnut Creek, Calif, assignors to Shell Oil Company, New York, N.Y., a corporation of Delaware No Drawing. Filed June 13, 1961, Ser. No. 116,668 9 Claims. (Cl. 44-63) This invention relates to fuel compositions for internal combustion engines, especially gasoline, and more particularly to gasoline containing deposit modifiers or ignition control compounds of phosphorus and/ or boron. The invention particularly relates to such fuel compositions which have improved characteristics with regard to octane number requirement increase of the engine in which they are used.

During the operation of internal combustion engines, a considerable amount of deposits accumulates on the various areas of the combustion chamber. This accumulation of deposits usually causes, or at least contributes to, an increase in the octane number requirement of the engine. That is, whereas the clean engine is capable of essentially knock-free operation on a fuel of lower octane number, after the engine has been run for some time and has thus accumulated deposits in the combustion chamber, it then requires a fuel of higher octane number to maintain essentially knock-free operation. The character of combustion chamber deposits may vary widely and depends upon a large number of variables such as (1) manner in which the engine is run, (2) fuel composition, and (3) amount and character ofthe additives in the gasoline. The first of these three variables is not susceptible to strict control. The manner in which the engine is run is largely determined by the service to which an engine is sub concentrations up to 4 cc. per U.S. gallon in motor gasv oline and up to 6 cc. per U.S. gallon in aviation gasoline;

Other organo-metallic antiknock additives which may be used are such materials as cyclopentadienyl nickel nitrosyl, .methylcyclopentadienyl manganese tricarbonyl,

iron pentacarbonyl, tris(acetylacetonate) iron, nickel 2- ethyl salicylate, bis(n-butyl salicylaldimine) nickel, vanadium acetylacetonate, ferrocenes and the like. However, because of the rise in criticality of ignition control problems such as pre-iginition, wild ping, and rumble or pounding, in modern automotive engines, better gasolines today also contain certain ignition control additives. The

most effective of the ignition control additives in use currently, and those with which the invention is concerned, are compounds of phosphorus and, to a lesser extent, compounds of boron.

taining 'halohydrocarbon scavengers are alkaryl phosphates or phosphites as in Yust et al., U.S. 2,899,212, issued June 2, 1959; alicyclic phosphates as shown in Yust.v

et al., U.S. 2,765,220, issued October 2, 1956;, carbocyclic phosphorus compounds containing a direct carbon-tophosphorus bond as in Yust et al., U.S. 2,826,195, issued March 25, 1958; esterified thiophosphates and thiophosphites containing at least one alkaryl ester group as in Phosphorus compounds which are useful as ignition control additives in leaded gasolines con- Patented Aug. 11, 1964 Yust et al., U.S. 2,843,465, issued July 15, 1958; tri-heter-;

ocyclic phosphates as in Yust et al., U.S. 2,841,480, issued July 1, 1958; tri(beta-haloaliphatic) phosphitesand phosphates as in Kolka, U.S. 2,866,808, issued December 30, 1958; dimethyl monophenyl phosphates as in Orloif et al., U.S. 2,911,431, issued November 3, 1959; dimethyl monophenyl phosphates as in Orloff et al., U.S. 2,870,186, issued January 20, 1959; and alkyl phosphates and phosphites.

Among the boron compounds useful as additives for abnormal ignition control are oleophilic group-substituted heterocyclic compounds of boron and nitrogen as shown in Scott et al., U.S. 2,821,463, issued January 28, 1958;

cyclic esters of boric acid as in Garner, U.S. 2,940,839,.

issued June 14, 1960; alkyl boronic acids as in Darling, U.S. 2,710,251, issued June 7, 1955; and esters of alkane diols and boronic acids as in Darling, U.S. 2,710,252, issued June 7, 1955.

Such ignition control additives do not generally reduce the amount of combustion chamber deposits but rather they modify the deposits in such a manner as to reduce abnormal ignition phenomena, e.g., by lowering the electrical or thermal conductivity of deposits. Furthermore, such additives do not significantly reduce the tendency of the octane number requirement of the engine to increase.

It is therefore an object of the invention to provide an improved internal combustion engine fuel composition having reduced tendency to form combustion chamber deposits. It is also an object of the invention to provide such a fuel which will reduce the quantity of combustion chamber deposits which are laid down in such engines. It}

is a further object of the invention to provide a fuel composition which will reduce the tendency of the engine in which it is used to require higher octane number fuels to attain essentially knock-free performance as compared with clean engine performance. A still further object of the invention is to provide a new method of reducing the octane number requirement of engines already containing substantial quantities of combustion chamber deposits.

The attainment of these and other objects will be ap-' 1 parent from the detailed description of the invention,

' restricted aspect, it is an improved gasoline composition;

which broadly stated, is an improved gasoline type hydrocarbon fuel for internal combustion engines containing an organo-metallic antiknock compound and a small amount of an alkyl-substituted Z-pyrrolidone. In a more having reduced tendency to cause increased octane number requirement in engines, containing an organo-metallic antiknock compound, a boron or phosphorus ignition control compound, and a small amount of an alk'yl-substituted 2-pyrrolidone compound.

More specifically, the invention is an improved fuel composition for use in internal combustion engines consisting essentially of a stable gasoline composition boiling between about 30 F. and 425 F. containing an octane number-improving amount of organo-metallic antiknock compound, a minor amount of an ignition control phosphorus or boron compound, and mixtures thereof, and from 0.05 to 5.0% by weight of a'gasoline soluble alkyl-- substituted 2-pyrrolidone, that is an alkyl-substituted lowing structural formula:

wherein each R is selected from the group consisting'of a hydrogen atom and alkyl radicals having from 1 to 4 carbon atoms, inclusively, with the proviso that at least one of the Rs be an alkyl group thereby defining an alkylsubstituted 2-pyrrolidone. referred to hereafter as (I).

In yet another aspect of the invention it has been found that the above-described alkyl-substituted Z-pyrrolidones may be added directly to the carburetor or the combustion chamber in dilution with, for example, gasoline, and is effective for reducing both deposits and octane number requirement of engines which have been operated for extended periods on fuels containing ignition control additives of boron and/ or phosphorus.

I The surprising benefits which may be obtained from the use of the aforementioned alkyl-substituted 2-pyrrolidone compounds of formula I will be seen and the invention will be more fully understood from the following examples.

Example I A clean Oldsmobile CFR engine was operated on a commercial premium gasoline fuel containing 3 cc. per gallon (U.S.) of tetraethyllead as TEL Motor Mix and 0.3 T (theory) of phosphorus in the form of tricresyl phosphate. The octane number requirement of the clean engine was 97 Research octane numbers. In 170 hours of operation the octane number requirement of the engine rose in the first 20 hours of operation to about 99.5, declined slightly to 99 in the next 45 hours and then rose steadily to a requirement of about 101 Research octane number (RON) at the end of the 170 hour period. At

this time, 0.5% by weight of N-methyl-2-pyrrolidone was added to the fuel and the operation was continued for another 110 hours. During this latter period when the engine was operating on the same fuel to which the N- methyl-Z-pyrrolidone had been added, the octane number requirement of the engine declined from 101 to a level of 98 in less than 20 hours operation. After 300 hours of total operation had elapsed the octane requirement rose slightly to about 99, at which level it was maintained until completion of the test after 380 hours total time of operation. These results show a very dramatic decrease in octane number requirement resulting from the addition of one of the members of the class of materials of Formula I to the fuel containing an ignition control additive.

Example II Having shown that addition of an alkyl-substituted 2- pyrrolidone would reduce the octane number requirement (ONR) of an engine already containing equilibrium deposits and an increased ONR by the procedure of Example I, the following test was performed to confirm that such a material would reduce the amount of ONR increase in a clean engine as well as reduce such ONR in an engine already containing combustion chamber deposits.

The same clean Oldsmobile CFR engine as in Example I Was first operated on the same commercial premium motor gasoline containing 3 cc. per gallon (U.S.) of tetraethyllead as TEL Motor Mix, 0.3 T of phosphorus as tricresyl phosphate, and 0.5 by weight of N-methyl-Z-pyrrolidone. The ONR at the start of the test was 97. At the end of 170 hours of operation, the octane number requirement of the engine had risen only to 98.0 RON. At this point, the engine was switched over to an identical fuel composition but which contained only 0.25% by weight of the N-methyl-Z-pyrrolidone. The engine was then operated for about 115 hours on the fuel containing the lesser amount of the additive of Formula I during which time the octane requirement of the engine remained essentially constant at about 98 RON. At the completion of about 285 hours total operation, the engine was again changed over to an identical fuel composition but which contained no ORR additive. After the changeover to the fuel which did not contain the Formula I additive, the ONR of the engine remained essentially constant for an operating period of about 40 hours, after which it rose The above formula will be Example Ill To confirm that ring-substituted 2-pyrrolidoncs as well as the N-substituted 2-pyrrolidones were effective to reduce ONR, the following test was performed:

A clean Oldsmobile CFR engine was initially operated on a commercial premium motor gasoline containing 3 cc. per gallon (U.S.) of tetraethyllead as TEL Motor Mix. 0.3 T of phosphorus as tricresyl phosphate, but none of the Z-pyrrolidone additive. The ONR at the start of the test was 97. At the end of the 230 hours of operation, the ONR had increased to over 101. The engine was then operated for 170 additional hours on the same fuel to which had been added 0.5% by weight of 5-1nethyl-2-pyrrolidone. In the first 30 hours of operation on the gasoline containing the Formula I additive, the ONR dropped from above 101 to 99 and during the ensuing 140 hours of operation the ONR dropped further to a level of 98. The engine was then switched back to operation on the original fuel which did not contain any of the 2-pyrrolidone additive and was operated for hours thereon, at the end of this period the ONR had risen only about 0.5 octane number. At this time, the operation was discontinued and the combustion chamber was dismantled and cleaned of all deposits. Upon cleaning the engine and resuming operation for another 70 hours with gasoline which did not contain any Formula I additive, the ONR again rose sharply to over 101 within 50 hours of operation.

These results again showed a surprising residual effect of the Formula I additive in reducing octane number requirement, as well as the efiicacy of the ring alkyl-substituted materials.

It is not known whether the action of the formula I compounds is of purely physical nature or whether some chemical interaction of gasoline components also takes place. Certainly, the test results showing the residual beneficial effect of the material indicates more than a mere transitory solvent action by itself. If the action of the Formula I compounds were only that of a solvent it would be expected that similar materials having the same or higher solubility for lead salts would work as well.

Example IV A number of organic compounds having analogous structures or which contained the same functional groupings, each having a solubility for PbCl of at least the same order of magnitude as the Formula I compounds of the invention were tested in essentially the same manner as in the foregoing-examples. The results are set forth below in Table I.

Since lead chloride, which is formed from the decomposition of the tetraalkyllead and the ethylene dichloride scavenger, is a major component of combustion chamber deposits, it is evident that the efiicacy of the Formula I compounds in accordance with the invention is not due to solvent power alone. Moreover, it is apparent that the effective ORR agents of the invention are limited to alkyl-substituted Z-pyrrolidones. That is, unsubstituted 2- pyrrolidone, as shown in Table I, was not effective as an ORR agent. In fact, this material was found to polymerize under normal engine operating conditions, thereby increasing engine deposits and octane requirement rather than decreasing same. Further, it was found that when the alkyl substituents on the 2-pyrrolidone ring were greater than 4 carbon atoms in number, the effectiveness of the additive was markedly reduced. For example, N-octyl and N-phenyl-Z-pyrrolidone were found to be 1neffective when tested in essentially the same manner as in the foregoing examples.

That certain members of the class of materials defined by Formula I are effective ORR agents is surprising and wholly unexpected when the cyclic-substituted amides of the invention such as N-methyl-2-pyrrolidone are compared with linear disubstituted amides such as N, N d1- n-butyl-formamide and dimethyl acetamide. It is noted that in both classes ofcompound (i.e., cyclic and linear) the nitrogen atom is disubstituted, yet the linear disubstituted amides were found wholly ineifective as ORR agents, While the cyclic disubstituted nitrogen compounds of the invention produced an octane number reduction of '3 numbers (see Example I).

In addition, it has been determined that the Formula I compounds as defined hereinbefore is in fact a function of an unexpected interaction with the ignition control additive. See Example V.

Example V A clean CFR engine was operated on a commercial premium gasoline fuel containing only 3 cc. per gallon (U.S.) of tetraethyllead for a period of 173 hours. The fuel used in this initial test phase contained no ignition control additive. The engine was then changed'over to an identical fuel but which contained 0.5% by weight of N-methyl-Z-pyrrolidone. This operation was continued for 106 additional hours during which there was no detectable reduction in the octane number requirement of the engine. The engine was then switched to an otherwise identical fuel, but which contained, in addition to the tetraethyllead and the N-methyI-Z-pyrrolidone, 0.3 T of phosphorus as tricresyl phosphate. In 150 hours operation on the last named fuel, the octane number requirement of the engine was reduced by 2 and the quantity of deposits contained in the combustion chamber was reduced by 80%. Thus, though neither the added Formula I compounds of the invention, nor the ignition control additive exhibited any power to reduce octane number requirement when used alone, however, when both are combined in accordance with the invention, they co-act to reduce octane number requirement and combustion chamber deposits as-well. I

In each of the foregoing examples the Formula I additive was added into the combustion chamber by inclusion in small quantities in the fuel. When it is added in this manner, the material should be present in the gasoline in concentrations of at least 0.05% by weight and preferably at least 0.1% by weight. Though concentrations as high as 5% by weight are effective to reduce ONR, concentrations over 1.0% by weight are undesirable because of adverse side efiects, among which are the tendencies to form sludge and to plug the piston rings. To obtain the most effective results a concentration of from 0.1 to 0.6% by weight is preferred, a range of from 0.3 to 0.5 being particularly preferred to obtain both maximum deposits removal and reduction in ONR.

Though additions of the Formula I compound to the combustion chamber by means of the gasoline is probably the most convenient method of utilizing the unique properties of the additive, in still another aspect of the invention it has been found that similar benefits may be obtained by adding the compound only intermittently, but" in much larger concentrations, into the combustion chamber. additive in gasoline when added to the combustion chamber, for example, through the spark plug holes or through the intake valves of an engine which has been run for an extended time on a gasoline containing ignition control additives of boron and phosphorus and which contains equilibrium deposits from such operation, is effective to reduce octane number requirement therein. When at least 15 milliliters are added in the foregoing manner to each of the cylinders of an automobile engine, and the engine is then operated, a considerable portion of the deposits is removed and the octane number requirement of the engine is considerably reduced. Most effective distribution of the Formula I additive and most effective results therefrom are obtained by rapidly accelerating the engine immediately after adding the additive concentrate. Moreover, as might be expected from Examples II and III, the beneficial effect in ONR reduction is retained for a considerable period, for example, up to hours of further operation, without further addition of the additive concentrate. Though the foregoing amount of the additive concentrate may be added all at one time, it is preferable to add it in increments of, say, 5-15 smaller dosages over a 3060 minute period. In either case, when the additive is added in the concentrated form, none of the additive is required in the principal fuel supply.

The concentrated solution of the additive should contain at least 25% by volume of the Formula I additive in order to get significant benefits. However, the con-' centrate should not contain over about 75% by volume of the additive. At higher concentrations the effect of the additive is relatively low per unit of concentrate added due, in large part, to maldistribution to the various parts of the combustion chamber. Therefore, a 50/50 mixture of the Formula I additive and diluent is preferred.

As diluent for the additive concentrate any non-viscous readily burnable organic compound in which the additive is soluble may be used. However, for reasons of both economics and availability, it is preferred to use a hydrocarbon fuel therefor. When gasoline is used as the dilucut, it may contain additives such as tetraethyllead and ignition control compounds, however these are not required.

Example V I A single cylinder laboratory engine containing a considerable quantity of equilibrium combustion chamber deposits was operated at a moderate speed, moderate loadidle cycle. The fuel therefor was a commercial premium fuel containing tetraethyllead (motor mix) and phos A 1957 Mercury engine was operated on a commercial premium fuel of the same type as used in the previous examples, which contained no Formula I additive. ing this time a considerable quantity of combustion chamber deposits had been built up and the amount of such deposits had reached an equilibrium. Three cylinders of thisrengine were treated by injecting .a.50% mixture. of N-methyl 2-pyrrolidone and commercial premium fuel through the spark plug holes. After replacing the plugs and allowing the engine to stand for 15 minutes, accelerating the engine several times removed almost all of the piston top deposits and all but a small portion of the deposits on the heads and inlet valves. V

The data in Exa'mple'IV, of course, show a definite cooperative.actionbetween the Formula I additive and the Thus, a concentrated solution of the Formula I ignition control additive. However, these data also show an extreme configurational criticality as to the Formula I compounds which may be used in accordance with the invention. The scope of useful compounds for use in the invention are thus quite narrowly limited to the class of alkyl-substituted 2-pyrrolidone compounds as defined hereinbefore. However, in addition to such structural limitations, it has been found that the volatility even of the members within this class is also critical. Accordingly, it has been found that members of the class of alkylsubstituted 2-pyrrolidone compounds which have a boiling point of below about 350 F. or above about 600 F. are substantially ineffective for use in accordance with the invention. It is therefore preferred to employ only those compounds having a boiling point between about 350 F. and 550 F. Particularly when the additive is to be used in the gasoline rather than by direct injection, it is preferred that the Formula I compound boil at approximately 500 F.

It will, of course, be recognized by anyone skilled in the art of fuels technology that the composition of the gasoline fuel is not at all critical as regards hydrocarbon type or the use of non-hydrocarbon constituents such as alkanols and alkyl ethers and the use of other types of additives. Thus any practicable stable motor gasoline fuel may be employed so long as it contains an operable amount of the ignition control additive, which will usually be from about 0.1 to 2.0 T when the ignition control additive is a phosphorus compound, and from about 0.5 to T when the ignition control additive is a boron compound.

As applied to the phosphorus ignition control compound, the term theory designates the amount required to react stoichiometrically with the lead so that all of the lead atoms and all of the phosphorus atoms form Pb (PO As applied to the boron ignition control compound, the term theory designates the amount required to react stoichiometrically with the lead so that all of the lead atoms and all of the boron atoms from Pb (BO It will, of course, be recognized that when other organo-metallic antiknock compounds which contain no lead are used, the term theory refers to the stoichiometric amount of phosphorus or boron which will react with the metal in the organo-metallic antiknock compound to form the analogous metal phosphates or orthoborates.

Besides the aforementioned ignition control compounds, lead scavengers, and organo-metallic antiknock compounds, the fuel compositions of the invention can, and ordinarily will, contain other additives, for example, dyes, oxidation inhibitors such as N,N'-ditertiarybutyl-4-methylphenol, metal derivators such as N,N-disalicylal-l,2- propanediamine, and rust inhibitors such as polymerized linoleic acids and N,C-disubstituted imidazolines, and the like. In addition, the fuel compositions of the invention may also contain small amounts of various supplemental or co-antiknock compounds which are employed to enhance the antiknock action of the primary antiknock additives. These co-antiknock compounds may be organometallic in nature, such as iron pentacarbonyl, methyl cyclopentadienyl manganese tricarbonyl, and cyclopentadienyl nickel nitrosyl, or they may be primarily organic in nature, such as tertiary butyl acetate.

The following are illustrative examples of compositions suitable for use according to the invention:

Example VIII Gasoline containing tetraethyllead, 1.0 theory ethylene dibromide, 0.3 theory tricresyl phosphate, and 0.5% by weight 4,5-butyl-2-pyrrolidone.

Example IX Gasoline containing tetraethyllead, 0.5 theory ethylene dibromide, 1.0 theory ethylene dichloride, 1.52 theories of bis(2-methyl-2,4-pentanediol)meso-borate, 0.18 theories 8 of tricresyl phosphate, and 0.25% by weight 3,5-diethyl-2- pyrrolidone.

Example X Gasoline containing tetramethyllead, 1.0 theory ethylene dibromide, 1.0 theory ethyI-Z-methylpentane 2,4 diol borate, and 0.5% by weight N-propyl-Z-pyrrolidone.

Example XI Gasoline containing tetraethyllead, 0.5 theory ethylene dibromide, 1.0 theory ethylene dichloride, 0.6 theory S,S, S-tricresyl thiophosphate, and 0.8% by weight 4,4-dimethyl-Z-pyrrolidone.

Example XII Gasoline containing tetraethyllead, 0.3 theory tricresyl phosphate, and 0.5% by weight 5-methyl-2-pyrrolidone.

Example XIII Gasoline containing methylcyclopentadienyl manganese tricarbonyl, 0.3 theory tricresyl phosphate, and 0.5% by weight N-methyl-Z-pyrrolidone.

Example XIV Gasoline containing tetraethyllead, 0.3 theory tricresyl phosphate, 1.0 theory ethylene dibromide, and 0.4% by weight of 4,5-n-propyl-2-pyrrolidone.

Example XV Gasoline containing tetraethyllead, 0.5 theory ethylene dibromide, 1.0 theory ethylene dichloride, and 1.0% by weight of 5-isobutyl-2-pyrrolidone.

Example XVI Gasoline containing tetraethyllead, 0.2 theory tris (chloropropyl) thionophosphate, and 0.3% by weight of 3,S-ditertiarybutyl-Z-pyrrolidone.

Example XVII Gasoline containing tetraethyllead, 0.5 theory ethylene dibromide, 1.0 theory ethylene dichloride, 0.2 theory tricresyl phosphate, and 0.8% by weight N-methyl-S-ethyl- 2-pyrrolidone.

Example XVIII Gasoline containing tetraethyllead, 0.5 theory ethylene dibromide, 1.0 theory ethylene dichloride, 0.3 theory tri- (chloroethyl) phosphate, and 0.5% by weight of 3-methyl- 2-pyrrolidone.

Example XIX Gasoline containing tetraethyllead, 0.5 theory ethylene dibromide, 1.0 theory ethylene dichloride, 0.4 theory cresyl diphenyl phosphate, and 0.05% by weight 3,4-dimethyl-Z-pyrrolidone.

This application is a continuation-in-part of our application Serial No. 57,906, filed September 23, 1960, now abandoned.

We claim as our invention:

1. An improved fuel composition for use in internal combustion engines consisting essentially of a stable gasoline boiling between about 30 F. and 425 F. containing an octane number-improving amount of an organo-metallic primary antiknock agent, a minor amount of an ignition control additive selected from the group consisting of phosphorus and boron compounds and mixtures thereof, and from 0.05 to 5.0% by weight of a gasoline-soluble alkyl-substituted 2-pyrrolidone compound having the structural formula wherein R is selected from the group consisting of hydrogen and alkyl radicals having from 1 to 4 carbon atoms in- 9 clusively with the proviso that at least one of the Rs be an alkyl radical.

2. The composition of claim 1 which contains from 0.05 to 1.0% by weight of the alkyl-substituted 2-pyrrolidone compound.

3. The composition of claim 1 in which the alkyl-substituted 2-pyrrolidone compound is N-methyl-Z-pyrrolidone.

4. The composition of claim 1 in which the alkyl-substituted 2-pyrrolidone compound is 5-methyl-2-pyrrolidone.

5. The composition of claim 1 in which the organometallic primary antiknock agent is methylcyclopentadienyl manganese tricarbonyl.

6. The composition of claim 1 in which the organometallic primary antiknock agent is a tetraalkyl lead antiknock agent.

7. The composition of claim 1 in which the organometallic primary antiknock agent is tetramethyllead.

8. The composition of claim 1 in which the organometallic primary antiknock agent is tetraethyllead.

9. A new method for reducing combustion chamber deposits and octane number requirement of engines containing combustion chamber deposits formed during operation of the engine on gasoline fuel containing an ignition control additive selected from the group consisting of compounds of phosphorus, boron, and mixtures there of, which comprises adding at least 15 milliliters of a gasoline fuel, containing dissolved therein from about 25 to about 75% by volume of a gasoline-soluble alkyl-substituted Z-pyrrolidone compound, directly to the combustion chambers of said engine and operating the engine.

References Cited in the file of this patent UNITED STATES PATENTS 1,524,674 Sadtler Feb. 3, 1925 1,908,705 Iaeger May 16, 1933 2,737,538 Nelson Mar. 6, 1956 FOREIGN PATENTS 1,020,209 Germany Nov. 28, 1957 

1. AN IMPROVED FUEL COMPOSITION FOR USE IN INTERNAL COMBUSTION ENGINES CONSISTING ESSENTIALLY OF A STABLE GASOLINE BOILING BETWEEN ABOUT 30*F. AND 425*F. CONTAINING AN OCTANE NUMBER-IMPROVING AMOUNT OF ANORGANO-METALLIC PRIMARY ANTIKNOCK AGENT, A MINOR AMOUNTOF AN IGNITION CONTROL ADDITIVE SELECTED FROM THE GROUP CONSISTING OF PHOSPHORUS AND BORON COMPOUNDS AND MIXTURES THEREOF, AND FROM 0.05 TO 5.0% BY WEIGHT OF A GALOLINE-SOLUBLE ALKYL-SUBSTITUTED 2-PYRROLIDONE COMPOUND HAVING THE STRUCTURAL FORMULA 